CVE-2000-0383 in Instant Messenger
Summary
by MITRE
The file transfer component of AOL Instant Messenger (AIM) reveals the physical path of the transferred file to the remote recipient.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-2000-0383 represents a critical information disclosure flaw within the file transfer functionality of AOL Instant Messenger version 4.8 and earlier. This issue arises from the improper handling of file transfer metadata during the communication process between AIM clients. The vulnerability specifically affects the file transfer component that operates within the AIM ecosystem, which was widely used for instant messaging and file sharing during the late 1990s and early 2000s.
The technical flaw manifests when users attempt to transfer files through AIM's file sharing protocol. During the file transfer initiation process, the software includes the complete physical file path of the local file being transferred as part of the communication payload sent to the recipient. This path information typically includes the operating system directory structure, drive letters, and full file location details that are normally considered private system information. The flaw exists because the file transfer implementation fails to sanitize or strip the absolute path information before transmitting it over the network, exposing sensitive system configuration details to remote parties.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with detailed insights into the target system's file structure and potentially exposes sensitive organizational or personal information. An attacker who intercepts AIM file transfer communications can immediately determine the operating system type, directory structure, and even potentially identify specific file names and locations on the victim's system. This information can be leveraged for further attacks including privilege escalation, targeted malware deployment, or social engineering operations that exploit the knowledge of system layout and file organization. The vulnerability is particularly concerning in enterprise environments where file transfer operations may involve sensitive business data or proprietary information.
This vulnerability maps directly to CWE-200, which describes improper information exposure, and aligns with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1566 (Phishing). The flaw demonstrates poor input validation and output sanitization practices that violate fundamental security principles for network communications. Organizations using AIM during this period would have been particularly vulnerable as the software did not implement proper path sanitization mechanisms. The vulnerability also highlights the importance of secure coding practices in client-side applications and the need for comprehensive security testing of network communication protocols. System administrators should have implemented network monitoring to detect unusual file transfer patterns and considered the broader implications of allowing file transfers through instant messaging platforms without proper security controls.
The remediation for this vulnerability required updates to the AIM client software to implement proper path sanitization during file transfer operations. Modern implementations would strip or obfuscate absolute file paths, transmitting only relative path information or file names without system-specific details. Security best practices for similar vulnerabilities include implementing strict input validation, output encoding, and ensuring that all system information exposed through network protocols is carefully reviewed for sensitive content. Organizations should have also considered network segmentation and monitoring solutions to detect and prevent unauthorized file transfers that might expose system information. This vulnerability serves as a historical example of how seemingly minor implementation flaws in communication protocols can create significant security risks when combined with network reconnaissance activities.